1. Field of the Invention
The present invention relates to a vacuum switchgear, and more particularly, to a multi circuit type vacuum switchgear having plural main circuit switches in a non-earthed vacuum chamber or chambers.
2. Description of Related Art
A multi circuit type vacuum switchgear is used in, e.g., an electric distribution system for electrical distribution to the demanding side. This type of vacuum switch gear has plural main circuit switches in a non-earthed vacuum chamber or chambers.
Patent Document 1 discloses a vacuum switchgear comprising a mold portion in which a conductor connected with a fixed electrode side of a vacuum switch is molded with resin, and a vacuum chamber which encases the switch having the fixed electrode and a movable electrode that can connect with and separate from the fixed electrode.
Patent Document 2 discloses a switchgear comprising a vacuum chamber, which encases a switch or plural switches for connecting with and separating from fixed electrodes and movable electrodes which connect with different outer conductors and which is molded and protruded out of an insulator. Plural terminals for connecting the fixed electrodes and the movable electrodes with the outer conductors project from the mold portion.
Patent Document 3 discloses a vacuum isolated switchgear comprising a vacuum chamber and a necessary number of switches encased in the vacuum chamber, in which the vacuum chamber is formed of metal materials and is covered with mold of insulating materials.
Patent Document 4 discloses a switchgear whose main circuit switches each having fixed side electrode and movable side electrode are encased in a vacuum chamber and the corresponding main circuit conductors thereof are installed through a wall of the vacuum chamber.    Patent Document 1: Japanese Patent Laid-open No. 2006-238522    Patent Document 2: Japanese Patent Laid-open No. 2000-306474    Patent Document 3: Japanese Patent Laid-open No. 2001-126595    Patent Document 4: Japanese Patent Laid-open No. 2001-135207
The above-described multi circuit type vacuum switchgear has a function for connection change in accordance with change of power load capacity on the power demanding side. If the withstand voltage performance of the vacuum switchgear becomes low, the devices on the downstream side are much influenced.